The present invention relates to a method and a device for stainless steel production without electrical energy supply on the basis of liquid pig-iron and FeCr solids, wherein, after a pretreatment in a blast furnace and a DDD treatment (dephosphorization, desiliconization, desulpherization) in a DDD installation, the liquid pig-iron is subsequently heated, refined or alloyed in an AOD converter, is reduced and finally an adaptation/adjustment of the treated steel melt is carried out in a ladle furnace.
The use of an AOD converter for manufacturing noble steels is already known. Thus WO 02/075003 describes a control method based on a continuous measurement of exhaust gases in combination with a computer and a dynamic model by means of which the necessary blow rates of oxygen and inert gas as well as the material charges are controlled.
EP 1 310 573 A2 discloses a method for manufacturing a metal melt, particularly for quenching a metal melt for manufacturing, for example, alloyed stainless steel or noble steel in an AOD converter, wherein the method is based on a computer technology which takes place in accordance with a processed model and which controls the metallurgical installation, the process model describes the behavior for at least one variable process parameter between a first process value, an adjusting value, and a final process value. An example describes the process sequence for manufacturing a steel of the class AISI 304.
Stainless steels of the ferritic steel group AISI 4xx are conventionally always manufactured from scrap the type the EAF and are later additionally alloyed and decarbonized in the AOD converter. In order to utilize the use of pig-iron, pig-iron pretreated in a steel mill with scrap and alloy melted into the pig-iron is mixed in a ladle outside of the furnace and is then charged into the converter.
WO 2006/050963 A2 proposes a method for producing stainless steel of the ferritic steel group AISI 4xx, particularly the steel group AISI 430, on the basis of liquid pig-iron and FeCr solids, with a DDD process line and the AOD converter with successively carried out method steps:                Pretreatment of the liquid pig-iron in the blast furnace, DDD treatment of the pig-iron in a suitable DDD installation, and charging the AOD converter with slag-free liquid pig-iron,        Heating, refining/alloying, and reducing the liquid pig-iron in the AOD converter,        Final adaptation/adjustment of the treated steel melt in the casting ladle.        
In this known method, the manufacture of the stainless steel is carried out advantageously with the use of the AOD converter without the use of an EAF, i.e., without the supply of electrical energy. However, this known method has the disadvantage that finally, because of the lack of energy in this method, only the manufacture of ferritic steels is possible.
Starting from this prior art, the object of the invention resides in utilizing the method known from WO 2006/050963 A2 with AOD technology for directly charging the pig-iron and subsequent alloying in the converter for the production of stainless steel of all stainless qualities in the austenitic as well as in the ferritic range with the use of autogenic chemical energy.